U.S. patent application number 17/282262 was filed with the patent office on 2021-07-29 for process for manufacturing an aluminium alloy part.
The applicant listed for this patent is C-TEC Constellium Technology Center. Invention is credited to Bechir CHEHAB.
Application Number | 20210230716 17/282262 |
Document ID | / |
Family ID | 1000005537830 |
Filed Date | 2021-07-29 |
United States Patent
Application |
20210230716 |
Kind Code |
A1 |
CHEHAB; Bechir |
July 29, 2021 |
PROCESS FOR MANUFACTURING AN ALUMINIUM ALLOY PART
Abstract
A process for manufacturing a part comprising a formation of
successive metal layers, superimposed on one another, wherein each
layer is formed by the deposition of a filler metal, the filler
metal being subjected to an input of energy so as to melt and to
constitute said layer by solidifying, the process being
characterized in that the filler metal is an aluminium alloy
comprising the following alloy elements (% by weight):--Fe: 2% to
8%, and preferably 2% to 6%, more preferentially 3% to
5%;--optionally Zr: 0.5% to 2.5% or 0.5% to 2% or 0.7% to
1.5%;--optionally Si: <1%, or even <0.5% or even <0.2% or
even <0.05%;--optionally Cu: 0.5%, or even <0.2%, or even
<0.05%;--optionally Mg: 0.2%, preferably 0.1%, preferably
<0.05%;--optionally other alloy elements <0.1% individually
and in total <0.5%;--impurities: <0.05%, or even <0.01%
individually, and in total <0.15%; remainder aluminium.
Inventors: |
CHEHAB; Bechir; (Voiron,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
C-TEC Constellium Technology Center |
Voreppe |
|
FR |
|
|
Family ID: |
1000005537830 |
Appl. No.: |
17/282262 |
Filed: |
October 3, 2019 |
PCT Filed: |
October 3, 2019 |
PCT NO: |
PCT/FR2019/052348 |
371 Date: |
April 1, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2998/10 20130101;
B33Y 70/00 20141201; B22F 10/20 20210101; B33Y 40/20 20200101; C22C
1/0416 20130101; C22C 21/00 20130101; B22F 2003/248 20130101 |
International
Class: |
C22C 1/04 20060101
C22C001/04; B33Y 40/20 20060101 B33Y040/20; B33Y 70/00 20060101
B33Y070/00; B22F 10/20 20060101 B22F010/20; C22C 21/00 20060101
C22C021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 5, 2018 |
FR |
1871133 |
Jul 30, 2019 |
FR |
1908678 |
Claims
1. A process for manufacturing a part including a formation of
successive metal layers, which are superimposed on each other, each
layer being formed by depositing a filler metal, the filler metal
being subjected to a supply of energy so as to become molten and to
constitute, upon solidifying, said layer, the process being wherein
the filler metal is an aluminum alloy including the following alloy
elements (% by weight); Fe: 2% to 8%, and optionally 2% to 6%,
optionally 3 to 5%; optionally Zr: 0.5% to 2.5% or 0.5 to 2% or 0.7
to 1.5%; optionally Si: <1%, or <0.5% or <0.2%, or
<0.05%; optionally Cu: 0.5%, or <0.2%, or <0.05%;
optionally Mg: 0.2%, optionally .ltoreq.0.1% optionally <0.05%;
optionally other alloy elements <0.1% individual and in total
<0.5%; impurities: <0.05%, or <0.01% individually, and in
total <0.15%; remainder aluminum.
2. The process according to claim 1, wherein the other alloy
elements are selected from: Cr, V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni,
Zn, Hf, Nd, Ce, Co, La, Ag, Li, Y, Yb, Er, Sn, In, Sb, Sr, Ba, Bi,
Ca, P, B and/or mischmetal.
3. The process according to claim 1, wherein Zr: <0.5% or Zr
<0.2% or Zr <0.05%.
4. The process according to claim 1, wherein mass fraction of each
other alloy element is less than 300 ppm, or less than 200 ppm, or
less than 100 ppm.
5. The process according to claim 1, wherein: Fe: 2% to 8%; Zr:
0.5% to 2.5%; Si: <0.5%.
6. The process according to claim 1, wherein: Fe: 2% to 8%; Zr:
<0.5%; Si: <0.5%.
7. The process according to claim 1, including, following formation
of the layers, an application of a thermal treatment.
8. The process according to claim 7, wherein the thermal treatment
is an aging or an annealing, performed at a temperature optionally
from 200.degree. C. to 500.degree. C.
9. The process according to any claim 7, wherein the thermal
treatment is performed: at a temperature from 200.degree. C. to
less than 400.degree. C., optionally from 320 to 380.degree. C., in
which case the duration of the thermal treatment is from 0.1 h to
20 h; or at a temperature from 400.degree. C. to 500.degree. C., in
which case the duration of the thermal treatment is from 0.1 h to 5
h;
10. The process according to claim 7, including no quenching
following formation of the layers or the thermal treatment.
11. The process according to claim 1, wherein the filler metal
takes the form of a powder, the exposure of which to a light beam
or charged particles results in a localized melting followed by a
solidification, so as to form a solid layer.
12. The process according to claim 1, wherein the filler metal is
obtained from a filler wire, the exposure of which to a heat source
results in a localized melting followed by a solidification, so as
to form a solid layer.
13. Part obtained by a process according to claim 1.
14. Powder, as a filler material of an additive manufacturing
process, wherein said powder is formed from an aluminum alloy,
including the following alloy elements by (% by weight): Fe: 2% to
8%, and optionally 2% to 6%, more optionally 3 to 5%; optionally
Zr: 0.5% to 2.5% or 0.5 to 2% or 0.7 to 1.5%; optionally Si:
<1%, or <0.5% or <0.2%, or <0.05%; optionally Cu: 0.5%,
or <0.2%, or <0.05%; optionally Mg: 0.2%, optionally 0.1%,
optionally <0.05%; optionally other alloy elements <0.1%
individual and in total <0.5%; impurities: <0.05%, or
<0.01% individually, and in total <0.15%; remainder aluminum.
Description
TECHNICAL FIELD
[0001] The technical field of the invention is a process for
manufacturing an aluminum alloy part, using an additive
manufacturing technique.
PRIOR ART
[0002] Since the 1980s, additive manufacturing techniques have been
developed. They consist of forming a part by adding material, which
is the opposite of machining techniques, which are aimed at
removing material. Previously confined to prototyping, additive
manufacturing is now operational for manufacturing mass-produced
industrial products, including metallic parts. The term "additive
manufacturing" is defined as per the French standard XP E67-001 as
a set of processes for manufacturing, layer upon layer, by adding
material, a physical object from a digital object. The standard
ASTM F2792 (January 2012) also defines additive manufacturing.
[0003] Various additive manufacturing methods are also defined in
the standard ISO/ASTM 17296-1. The use of additive manufacturing to
produce an aluminum part, with a low porosity, was described in the
document WO2015006447. The application of successive layers is
generally carried out by applying a so-called filler material, then
melting or sintering the filler material using an energy source
such as a laser beam, electron beam, plasma torch or electric
arc.
[0004] Regardless of the additive manufacturing method applied, the
thickness of each layer added is of the order of some tens or
hundreds of microns.
[0005] Further additive manufacturing methods can be used. Let us
mention for example, and non-restrictively, melting or sintering a
filler material taking the form of a powder. This may consist of
laser melting or sintering. Patent application US20170016096
describes a process for manufacturing a part by localized melting
obtained by exposing a powder to an electron beam or laser beam
type energy, the process also being known as the acronyms SLM,
meaning "Selective Laser Melting", or "EBM", meaning "Electron Beam
Melting". The mechanical properties of aluminum parts obtained by
additive manufacturing are dependent on the alloy forming the
filler metal, and more specifically on the composition thereof as
well as on the thermal treatments applied following the
implementation of additive manufacturing.
[0006] The applicant determined an alloy composition which, used in
an additive manufacturing process, makes it possible to obtain
parts with remarkable mechanical performances, without it being
necessary to implement thermal treatments such as solution heat
treatments and quenching. Furthermore, the parts used have
advantageous thermal conductivity or electrical conductivity
properties. This makes it possible to diversify the application
possibilities of these parts.
DESCRIPTION OF THE INVENTION
[0007] The invention firstly relates to a process for manufacturing
a part including a formation of successive metal layers, which are
superimposed on each other, each layer being formed by depositing a
filler metal, the filler metal being subjected to a supply of
energy so as to become molten and to constitute, upon solidifying,
said layer, the process being characterized in that the filler
metal is an aluminum alloy including the following alloy elements
(% by weight); [0008] Fe: 2% to 8%, and preferably 2% to 6%, more
preferably 3 to 5%; [0009] optionally Zr: 0.5% to 2.5% or 0.5 to 2%
or 0.7 to 1.5%; [0010] optionally Si: <1%, or <0.5% or
<0.2%, or <0.05%; [0011] optionally Cu: 0.5%, or <0.2%, or
<0.05%; [0012] optionally Mg: 0.2%, preferably 0.1% preferably
<0.05%; [0013] optionally other alloy elements <0.1%
individual and in total <0.5%; [0014] impurities: <0.05%, or
<0.01% individually, and in total <0.15%; remainder
aluminum.
[0015] Preferably, the quantity of Fe is greater than the quantity
of Zr. Of the other alloy elements, mention can be made for example
of Cr, V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni, Zn, Hf, Nd, Ce, Co, La,
Ag, Li, Y, Yb, Er, Sn, In, Sb, Sr, Ba, Bi, Ca, P, B and/or
mischmetal. In a manner known to a person skilled in the art, the
composition of the mischmetal is generally from about 45 to 50%
cerium, 25% lanthanum, 15 to 20% neodymium and 5% praseodymium.
[0016] According to an alternative embodiment of the present
invention, there is no voluntary addition of Zn, particularly due
to the fact that it evaporates during the SLM process.
[0017] According to an alternative embodiment of the present
invention, the alloy is not an AA7xxx type alloy.
[0018] The process can include the following features, taken in
isolation or according to technically feasible combinations: [0019]
the alloy includes no Cr, V, Mn, Ti, Mo, or according to a mass
fraction less than 500 ppm, than 300 ppm, than 200 ppm, or less
than 100 ppm; [0020] the mass fraction of each other alloy element
is less than 500 ppm, or than 300 ppm, or than 200 ppm, or than 100
ppm; [0021] the mass fraction of Zr is strictly less than 0.5%, or
than 0.2% or than 0.05%; [0022] the mass fraction of Si is strictly
less than 0.5%, or than 0.2% or than 0.05%; [0023] Fe: 2% to 8% and
Zr: 0.5% to 2.5% and Si: <0.5%; [0024] Fe: 2% to 8% and Zr
<0.5% and Si: <0.5%; [0025] Fe: >3% and 8%.
[0026] Each layer can particularly describe a pattern defined on
the basis of a digital model. The process can include, following
the formation of the layers, an application of at least one thermal
treatment. The thermal treatment can be or include an aging or an
annealing, capable of being performed at a temperature preferably
from 200.degree. C. to 500.degree. C. The thermal treatment can
then be performed: [0027] at a temperature from 200.degree. C. to
less than 400.degree. C., preferably from 320 to 380.degree. C., in
which case the duration of the thermal treatment is from 0.1 h to
20 h; [0028] or at a temperature from 400.degree. C. to 500.degree.
C., in which case the duration of the thermal treatment is
preferably from 0.1 h to 5 h;
[0029] The thermal treatment can also include a solution heat
treatment and a quenching, although it is preferred to avoid them.
It can also include a hot isostatic compression. According to an
advantageous embodiment, the process includes no quenching,
following the formation of the layers or the thermal treatment.
Thus, preferably, the process does not include steps of solution
heat treatment followed by a quenching.
[0030] According to a further embodiment, the filler metal is
obtained from a filler wire, the exposure of which to a heat
source, for example an electric arc, results in a localized melting
followed by a solidification, so as to form a solid layer.
According to a further embodiment, the filler metal takes the form
of a powder, the exposure of which to a light beam or charged
particles results in a localized melting followed by a
solidification, so as to form a solid layer.
[0031] The invention secondly relates to a metal part, obtained
after applying a process according to the first subject matter of
the invention.
[0032] The invention thirdly relates to a filler metal,
particularly a filler wire or a powder, intended to be used as a
filler material of an additive manufacturing process, characterized
in that it is formed from an aluminum alloy, including the
following alloy elements (by weight): [0033] Fe: 2% to 8%, and
preferably 2% to 6%, more preferably 3 to 5%; [0034] optionally Zr:
0.5% to 2.5% or 0.5 to 2% or from 0.7 to 1.5%; [0035] optionally
Si: <1%, or <0.5% or <0.2%, or <0.05%; [0036]
optionally Cu: 0.5%, or <0.2%, or <0.05%; [0037] optionally
Mg: 0.2%, preferably 0.1% preferably <0.05%; [0038] optionally
other alloy elements <0.1% individual and in total <0.5%;
[0039] impurities: <0.05%, or <0.01% individually, and in
total <0.15%;
[0040] remainder aluminum.
[0041] The aluminum alloy forming the filler material can have the
features described in relation to the first subject matter of the
invention.
[0042] The filler material can be presented in the form of a
powder. The powder can be such that at least 80% of the particles
making up the powder have a mean size in the following range: 5
.mu.m to 100 .mu.m, preferably from 5 to 25 .mu.m, or from 20 to 60
.mu.m.
[0043] When the filler material is presented in the form of a wire,
the diameter of the wire can particularly be from 0.5 mm to 3 mm,
and preferably from 0.5 mm to 2 mm, and more preferably from 1 mm
to 2 mm.
[0044] Further advantages and features will emerge more clearly
from the following description of specific embodiments of the
invention, given by way of non-limiting examples, and represented
in the figures listed below.
FIGURES
[0045] FIG. 1 is a diagram illustrating an SLM type additive
manufacturing process.
[0046] FIG. 2 illustrates the tensile and electrical conduction
properties determined during experimental tests, using samples
manufactured using an additive manufacturing process according to
the invention.
[0047] FIG. 3 is a diagram illustrating a WAAM type additive
manufacturing process.
[0048] FIG. 4 is a diagram of the cylindrical TOR4 type test
specimen used according to the examples.
[0049] FIG. 5 is a diagram of the two test parts of the
example.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0050] In the description, unless specified otherwise: [0051]
aluminum alloys are designated according to the nomenclature of the
Aluminum Association; [0052] the chemical element contents are
designated as a % and represent mass fractions. The notation x %-y
% means greater than or equal to x % and less than or equal to y
%.
[0053] Impurity denotes chemical elements unintentionally present
in the alloy.
[0054] FIG. 1 schematically represents the operation of a Selective
Laser Melting (SLM) additive manufacturing process. The filler
metal 15 is presented in the form of a powder disposed on a support
10. An energy source, in this case a laser source 11, emits a laser
beam 12. The laser source is coupled with the filler material by an
optical system 13, the movement whereof is determined according to
a digital model M. The laser beam 12 is propagated along a
propagation axis Z, and follows a movement along a plane XY,
describing a pattern dependent on the digital model. The plane is
for example perpendicular to the propagation axis Z. The
interaction of the laser beam 12 with the powder 15 induces
selective melting thereof, followed by a solidification, resulting
in the formation of a layer 20.sub.1 . . . 20.sub.n. When a layer
has been formed, it is coated with filler metal powder 15 and a
further layer is formed, superimposed on the layer previously
produced. The thickness of the powder forming a layer can for
example be from 10 to 200 .mu.m.
[0055] The powder can have at least one of the following features:
[0056] Mean particle size from 5 to 100 .mu.m, preferably from 5 to
25 .mu.m, or from 20 to 60 .mu.m. The values given signify that at
least 80% of the particles have a mean size within the specified
range. [0057] Spherical shape. The sphericity of a powder can for
example be determined using a morphogranulometer. [0058] Good
castability. The castability of a powder can for example be
determined as per the standard ASTM B213 or the standard ISO 4490
:2018. According to the standard ISO 4490:2018, the flow time is
preferably less than 50 s. [0059] Low porosity, preferably from 0
to 5%, more preferably from 0 to 2%, even more preferably from 0 to
1% by volume. The porosity can particularly be determined by
optical micrograph image analysis or by helium pycnometry (see the
standard ASTM B923). [0060] Absence or small quantity (less than
10%, preferably less than 5% by volume) of small, so-called
satellite, particles (1 to 20% of the mean size of the powder),
which adhere to the larger particles.
[0061] The use of such a process enables a manufacture of parts
according to a high yield, of up to 40 cm.sup.3/h.
[0062] The applicant observed that applying thermal treatments such
as quenching could induce distortion of the part, due to the sudden
temperature variation. The distortion of the part is generally all
the more significant as the dimensions thereof are large. Yet, the
advantage of an additive manufacturing process is specifically that
of obtaining a part wherein the shape, after manufacturing is
definitive, or virtually definitive. The occurrence of a
significant deformation resulting from a thermal treatment is
therefore to be avoided. By virtually definitive, it is understood
that finishing machining can be performed on the part after the
manufacturing thereof: the part manufactured by additive
manufacturing extends according to the definitive shape thereof,
apart from the finishing machining.
[0063] Having observed the above, the applicant sought an alloy
composition, forming the filler material, making it possible to
obtain acceptable mechanical properties, without requiring the
application of thermal treatments, subsequent to the formation of
the layers, liable to induce distortion. The aim is particularly to
avoid thermal treatments involving a sudden temperature variation.
Thus, the invention makes it possible to obtain, by additive
manufacturing, a part wherein the mechanical properties are
satisfactory, in particular in terms of yield strength. According
to the type of additive manufacturing process selected, the filler
material can be presented in the form of a wire or a powder.
[0064] The applicant observed that, by limiting the number of
elements present in the alloy, above a content of 1%, a good
compromise between advantageous mechanical and thermal properties
is obtained. It is usually acknowledged that adding elements to the
alloy makes it possible to enhance certain mechanical properties of
the part produced by additive manufacturing. The term mechanical
properties denotes for example the yield strength or the elongation
at rupture. However, adding an excessively large quantity, or an
overly wide diversity, of chemical alloy elements can be
detrimental to the thermal conduction properties of the part
resulting from additive manufacturing. Thus, the use of binary or
ternary alloys, in an additive manufacturing process, represents a
promising avenue in the field of additive manufacturing.
[0065] The applicant considered that it was useful to reach a
compromise between the number and the quantity of elements added to
the alloy, so as to obtain acceptable mechanical and thermal (or
electrical) properties.
[0066] The applicant considers that such a compromise is obtained
by limiting to one or two the number of chemical elements forming
the aluminum alloy having a mass fraction greater than or equal to
1% or 0.5%. Thus, a particularly advantageous alloy can be obtained
by adding, according to a mass fraction greater than 1% or 0.5%:
[0067] only Fe, where Fe: 2% to 8%, in which case the alloy
essentially consists of two elements (Al and Fe); [0068] or Fe
(where Fe: 2% to 8%) and Zr (where Zr: 0.5% to 2.5%, in which case
the alloy essentially consists of three elements (Al, Fe and Zr).
The presence of Zr generally enhances the mechanical properties
after thermal treatment.
[0069] The alloy can also include other alloy elements, such as Cr,
V, Ti, Mn, Mo, W, Nb, Ta, Sc, Ni, Zn, Hf, Nd, Ce, Co, La, Ag, Li,
Y, Yb, Er, Sn, In, Sb, Sr, Ba, Bi, Ca, P, B and/or mischmetal
having individually a content <0.1% by weight. However, some of
these alloy elements, in particular Cr, V, Ti and Mo degrade the
conductivity, therefore it is preferable to avoid them. Cu is
considered the less harmful with regard to thermal
conductivity.
[0070] According to an alternative embodiment of the present
invention, there is no voluntary addition of Zn, particularly due
to the fact that it evaporates during the SLM process.
[0071] According to an alternative embodiment of the present
invention, the alloy is not an AA7xxx type alloy.
[0072] Adding Mg in the absence of a solution-heat
treatment-quenching-aging treatment, would lower the electrical or
thermal conductivity without a significant impact on the mechanical
properties. To this is added its tendency to evaporate during the
atomization and SLM process, especially for high-liquidus alloys
such as those tested according to the present invention. Thus,
according to an alternative embodiment, the alloy used according to
the present invention comprises no Mg or else according to an
impurity quantity, i.e. <0.05%. When the other alloy elements
are for example Y, Yb, Er, Sn, In, Sb, these elements are
preferably present individually according to a mass fraction
strictly less than 500 ppm, and preferably strictly less than 300
ppm, or 200 ppm, or 100 ppm. It should be noted that, preferably,
the alloys according to the present invention are not AA6xxx type
alloys, due to the lack of simultaneous addition of Si and Mg in
quantities greater than 0.2%.
[0073] Experimental Examples
[0074] A test was carried out using a binary alloy, in which the
composition included Fe 4%; impurities and other alloy elements:
<0.05% individually.
[0075] Test parts were produced by SLM, using an E05290 SLM type
machine (supplier EOS). The laser power was 370 W. The sweep rate
was 1400 mm/s. The deviation between two adjacent sweeping lines,
usually referred to as "vector deviation" was 0.11 mm. The layer
thickness was 60 .mu.m, with heating of the construction slab to
200.degree. C.
[0076] The powder used had a particle size essentially from 3 .mu.m
to 100 .mu.m, with a median of 40 .mu.m, a 10% fractile of 16 .mu.m
and a 90% fractile of 79 .mu.m.
[0077] First test parts were produced, in the form of vertical
cylinders with respect to the construction slab (Z direction) of
diameter 11 mm and height 46 mm. Second test parts were produced,
taking the form of parallelepipeds of dimensions 12 (X direction)
.times.45 (Y direction) .times.46 (Z direction) mm (see FIG. 5).
All the parts underwent a post-SLM manufacturing stress relief
treatment of 4 hours at 300.degree. C.
[0078] Some first parts underwent a post-manufacturing thermal
treatment at 350.degree. C., 400.degree. C. or 450.degree. C., the
treatment duration being from 1h to 104 h. All of the first parts
(with and without post-manufacturing thermal treatment) were
machined to obtain TOR4 type cylindrical tensile test specimens
having the following characteristics in mm (see Table 1 and FIG.
4): In FIG. 4 and Table 1, O represents the diameter of the central
portion of the test specimen, M the width of the two ends of the
test specimen, LT the total length of the test specimen, R the
radius of curvature between the central portion and the ends of the
test specimen, Lc the length of the central portion of the test
specimen and F the length of the two ends of the test specimen.
TABLE-US-00001 TABLE 1 Type .PHI. M LT R Lc F TOR 4 4 8 45 3 22
8.7
[0079] These cylindrical test specimens underwent tensile testing
at ambient temperature as per the standard NF EN ISO 6892-1
(2009-10).
[0080] Some of the second test parts underwent a post-manufacturing
thermal treatment, as described in relation to the first parts. The
second test parts were subjected to electrical conductivity tests,
on the basis that the electrical conductivity evolves similarly to
thermal conductivity. A linear dependency relationship of the
thermal conductivity and the electrical conductivity, according to
the Wiedemann-Franz, was validated in the publication by Hatch
"Aluminium properties and physical metallurgy" ASM Metals Park,
Ohio, 1988. The second test parts underwent surface polishing on
each side of 45 mm.times.46 mm with a view to conductivity
measurements using sandpaper of roughness 180. The electrical
conductivity measurements were made on the polished sides using a
Foerster Sigmatest 2.069 measuring apparatus at 60 kHz. Table 2
hereinafter shows, for each first test part, the thermal treatment
temperature (.degree. C.), the thermal treatment duration, the
yield strength at 0.2% Rp0.2 (MPa), the tensile strength (Rm), the
elongation at rupture A (%), as well as the electrical conductivity
(MS..sup.-1). The tensile properties (yield strength, tensile
strength and elongation at rupture) were determined using the first
test parts, along the manufacturing direction Z, whereas the
electrical properties (thermal conductivity) were determined on the
second test parts. In Table 2 hereinafter, the duration of Oh
corresponds to a lack of thermal treatment.
TABLE-US-00002 TABLE 2 Duration Temperature Rp0.2 Rm A .sigma. (h)
(.degree. C.) (MPa) (MPa) (%) (MS/m) 0 -- 282 405 4.5 24.64 1 400
262 378 7.4 24.84 4 400 217 313 11.3 26.5 10 400 187 362 14.7 27.57
100 400 152 303 22 28.93 104 450 136 272 18.6 29.82 14 350 268 228
6.2 25.51 56 350 215 199 9.9 25.61
[0081] In the absence of thermal treatment, the yield strength
Rp0.2 attains 282 MPa, and the elongation at rupture is equal to
4.5%. Applying a thermal treatment makes it possible to lower the
yield strength, but it makes it possible to increase the electrical
conductivity and the elongation at rupture. It is observed that the
elongation at rupture is always greater than 3%. In the absence of
thermal treatment, the mechanical properties of the manufactured
part are considered to be satisfactory. When it is sought to favor
a compromise between the mechanical properties and the thermal or
electrical conduction properties, it is preferable to apply a
thermal treatment, and for example: [0082] from 200.degree. C. to
less than 400.degree. C., the duration being from 0.1 h to 20 h;
[0083] from 400.degree. C. to 500.degree. C., the duration being
from 0.1 h to 5 h;
[0084] When a thermal treatment is applied with a view to enhancing
the thermal or electrical conduction properties, it is preferable
for its temperature to be less than 500.degree. C. or preferably
less than 450.degree. C., and for example from 100.degree. C. to
450.degree. C. It can in particular consist of an aging or an
annealing. Its duration can exceed 10 hours, or even 100 hours.
FIG. 2 illustrates the tensile properties (Y-axis, representing the
yield strength Rp0.2) as a function of the thermal conductivity
properties (X-axis, representing the thermal conductivity).
[0085] It is recalled that the thermal conduction properties are
assumed to be representative of the electrical conduction
properties. In FIG. 2, the percentages indicate the elongation at
rupture. The term "No THT" means no thermal treatment.
[0086] Such a binary alloy has a relatively low liquidus
temperature (of the order of 660.degree. C.), which alloys a good
capability to be atomized using standard industrial atomizers for
aluminum alloys. The liquidus was determined using the powder.
[0087] The relative density of the samples is greater than 99%,
which conveys a porosity <1% measured by image analysis on a
polished sample section.
[0088] According to an embodiment, the process can include a hot
isostatic compression (HIC). The HIC treatment can particularly
make it possible to enhance the elongation properties and the
fatigue properties. The hot isostatic compression can be carried
out before, after or instead of the thermal treatment.
Advantageously, the hot isostatic compression is carried out at a
temperature of 250.degree. C. to 500.degree. C. and preferably of
300.degree. C. to 450.degree. C., at a pressure of 500 to 3000 bar
and for a duration of 0.5 to 50 hours.
[0089] The potential thermal treatment and/or the hot isostatic
compression makes it possible in particular to increase the
electrical or thermal conductivity of the product obtained.
[0090] According to a further embodiment, adapted to structural
hardening alloys, a solution heat treatment followed by a quenching
and an aging of the part formed and/or a hot isostatic compression
can be carried out. The hot isostatic compression can in this case
advantageously replace the solution heat treatment.
[0091] However, the process according to the invention is
advantageous, as it needs preferably no solution heat treatment
followed by quenching. The solution heat treatment can have a
harmful effect on the mechanical strength in certain cases by
contributing to growth of dispersoids or fine intermetallic
phases.
[0092] According to an embodiment, the method according to the
present invention further optionally includes a machining
treatment, and/or a chemical, electrochemical or mechanical surface
treatment, and/or a tribofinishing. These treatments can be carried
out particularly to reduce the roughness and/or enhance the
corrosion resistance and/or enhance the resistance to fatigue crack
initiation.
[0093] Optionally, it is possible to carry out a mechanical
deformation of the part, for example after additive manufacturing
and/or before the thermal treatment.
[0094] Though described in relation to an SLM type additive
manufacturing method, the process can be applied to other WAAM type
additive manufacturing methods, mentioned in relation to the prior
art. FIG. 3 represents such an alternative. An energy source 31, in
this case a torch, forms an electric arc 32. In this device, the
torch 31 is held by a welding robot 33. The part 20 to be
manufactured is disposed on a support 10. In this example, the part
manufactured is a wall extending along a transverse axis Z
perpendicularly to a plane XY defined by the support 10. Under the
effect of the electric arc 12, a filler wire 35 becomes molten to
form a weld bead. The welding robot is controlled by a digital
model M. It is moved so as to form different layers 20.sub.1 . . .
20.sub.n, stacked on one another, forming the wall 20, each layer
corresponding to a weld bead. Each layer 20.sub.1 . . . 20.sub.n
extends in the plane XY, according to a pattern defined by the
digital model M.
[0095] The diameter of the filler wire is preferably less than 3
mm. It can be from 0.5 mm to 3 mm and is preferably from 0.5 mm to
2 mm, or from 1 mm to 2 mm. It is for example 1.2 mm.
[0096] Further processes can also be envisaged, for example, and
non-restrictively: [0097] Selective Laser Sintering or SLS; [0098]
Direct Metal Laser Sintering or DMLS; [0099] Selective Heat
Sintering or SHS; [0100] Electron Beam Melting or EBM; [0101] Laser
Melting Deposition; [0102] Direct Energy Deposition or DED; [0103]
Direct Metal Deposition or DMD; [0104] Direct Laser Deposition or
DLD; [0105] Laser Deposition Technology; [0106] Laser Engineering
Net Shaping; [0107] Laser Cladding Technology; [0108] Laser
Freeform Manufacturing Technology or LFMT; [0109] Laser Metal
Deposition or LMD; [0110] Cold Spray Consolidation or CSC; [0111]
Additive Friction Stir or AFS; [0112] Field Assisted Sintering
Technology, FAST or spark plasma sintering; or [0113] Inertia
Rotary Friction Welding or IRFW.
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